View Single Post
Old 03-03-2012, 03:54 PM
jake's Avatar
jake jake is offline
Senior Member
Join Date: Nov 2007
Posts: 169
Crystal Radio Magic

Well it's not magic(sorry 4 the deception) but it is a radio, my first. It works and I can hear the one station I was hoping for; 1620kHz, 10,000 watts, 6 miles away.

I started this because of
Originally Posted by T-rex View Post
Here is how the contest works. We learn how to make a "Crystal Set", just as everybody should. It is a "Rite of Passage". A crystal set is an A.M. radio that uses no battery, the magnification factor of its tank circuit powers the radio. Hence it can be seen that the A.M. broadcast station's transmitted energy is powering the crystal set, JUST AS TESLA ENVISIONED. Wow Mr. Wizard that is fantastic. Let's start today.
Break more to follow
Problem: It was easy, very easy. No matter what I do I can hear this station. I was expecting to have to "tune in" this station. So instead I minimized the components. An inductor(300uH, 60 turns, 20gauge), 1N34 germanium diode, crystal ear bud, and antenna(just about everything works(10 feet of 20 gauge, my body, cookie sheet, and even a beer can)) Some work better than others.
No capacitor??? Holding the coil is the best capacitor I found.
No ground. If I connect it to ground I either get a 60Hz hum when I use a water pipe or lower volume if I stick 2 feet of 6 gauge in the ground. I guess that means I need a better ground. Off to home depot for 10' water pipes.

Two questions for the group: (the goal is to maximize the reception of 1620kHz with only a crystal ear piece)

-There are a number of online calculators that allow you to calculate capatance for a given inductance or inductance for a given capatance, both for a given frequency? What "ratio" works best? (is it better to have more capatance or more inductance).

-Ground-What is good enough? Does it keep getting better as your ground system grows and gets deeper. Is it better to go deeper or wider(radial star like Dollard describes) I have lots of clay around here and I am going to try to water drill with the copper pipe as it goes down. How much better would 20' be over 10'?

Ok more than 2 questions but I'm learning.
Attached Images
File Type: jpg simple radio.JPG (561.7 KB, 143 views)
Reply With Quote